Energy & Fuels 1991,5,855-860 probability of alkene incorporation. Figure 16, a and b, shows analyses of the pot liquid at the end of runs L and H. The normalized Schulz-Flory plots, with the carrier, CzaHbs,subtracted from the distributions, both show (Y values of 0.83. These represent the high molecular weight products that have accumulated throughout the run. The end-of-run slurry from the cobalt catalyst alone, operated over a wide range of conditions, exhibited an (Y of 0.87.’ These values of cy are comparable. Conclusions A Cu-ZnO/A1203 water gas shift catalyst was found to exhibit stable activity in a slurry reactor under typical Fischer-Tropsch conditions. The stability of the catalyst was not adversely affected by increased pressure, temperature, variation in in situ H2/C0 ratio, or the addition of l-butene, a representative Fischer-Tropsch product. In the presence of the shift catalyst, l-butene underwent considerable hydrogenation and isomerization, but did not crack. A Co/MgO/Si02 Fischer-Tropsch catalyst was operated in conjunction with this shift catalyst at two different [Co/MgO/Si02]/[Cu-ZnO/A1203] weight ratios, 0.27 and
855
0.51. Operating conditions were 240 O C , 0.79 MPa, and feed H&O ratios from 1.0 to 2.0 at 0.3 to 0.6 L(STP)/min. In both runs, the Fischer-Tropsch catalyst maintained steady-state activity for the entire run of about 400 h on stream at a level comparable to the cobalt catalyst operating alone. The rate of the Fischer-Tropsch reaction in the mixture followed a rate expression for the cobalt catalyst alone. The Cu-ZnO/A1203 WGS catalyst exhibited a very slow loss of its activity. Each mixed catalyst system exhibited stable long-term Fischer-Tropsch selectivity, but the presence of the WGS catalyst increased the extent of the secondary reactions, thereby lowering the overall selectivity to fuel range products. The feasibility of a mechanical mixture of a cobalt-based Fischer-Tropsch catalyst and a Cu-ZnO WGS catalyst in a slurry reactor has been established. Acknowledgment. This study was supported by the Office of Fossil Energy, US.Department of Energy, under contract No. DE-AC22-87PC79816, Registry No. Cu, 7440-50-8; ZnO, 1314-13-2; Co, 7440-48-4; MgO, 1309-48-4; CO, 630-08-0.
Mathematical Expressions of Some Nonadditive Properties of Gas Oil-Residual Fuel Blends E. Lois,* S. Stournas, and D. Karonis Fuels and Lubricants Laboratory, National Technical University, Zografou Campus, 157 73 Athens, Greece Received April 8, 1991. Revised Manuscript Received August 30, 1991 Mathematical expressions are presented for a number of nonadditive properties of gas oil-residual fuel blends, thus assisting the mixing processes in modem refineries. Experimental data were obtained from the pour point, flash point, and kinematic viscosity of a series of gas oil and residual fuel mixtures from different crudes and the resulta were compared with those computed from tabulated values used in industry. Subsequently, empirical expressions were developed to predict the tabulated blending indices, giving excellent correlations in all cases. Introduction The straight-run residual fuels produced by refineries, usually do not meet commercial specifications. The critical properties, i.e., pour point, flash point, viscosity, and sulfur content frequently do not meet the required specifications, the limits of which tend to become progressively more severe for operational and environmental reasons. Following production, the quality of the various residual fuel grades is adjusted by blending with lighter components, mainly gas oil or kerosine fractions. The blending procedure for most nonadditive properties is based on tabulated values of blending indices of the individual fracti0ns.I However, in automated processes, there is a need for mathematical expressions that would predict accurately the volumes of each component to be blended, to obtain the prescribed specifications. The pour point of fuel mixtures? because of its importance to the rheological characteristics of the final product, (1) Spien, H. M. Technical Data on Fuel, 6th ed.; The British National Committee, World Power Conference, 1961. (2) ‘Teat for Pour Point”, ASTM D 97-88; American Society for Testing and Materials, Philadelphia, PA, 1986.
has been extensively investigated in the past?+ and satisfactory correlations are presented for similar fuels,’ whereas the majority of the refineries use tabulated blending indices’ to evaluate the pour point of the mixture for dissimilar fractions. The same approach is followed to calculate the flash pointe of residual fuel-gas oil blends, where a number of different sets of blending indices are in use.’t9 The viscosity of fuel mixtures, since it is the most required property, is predicted either by graphical meth(3) Baxa, J.; Ghats, A. J. Ropa Uhlie 1988, 30(2), 86. (4) Ostashov, V. M.; bobrovskii, S. A.; Kurasov, A. E. Mosk. I M ~ . Neftekhim. Casou. Prom. 1971,97,124. (5) Ordovskaya, V. I.; Kraineva, I. N. Neftepererab.Neftekhim. 1989, 5, 31. (6) Kriehna, R.; Joehi, G. C.; Purohit, R. C.; Agrawal, K. M.; Verma, P. 5.;Bhattacharjee, S. Energy Fuels, 1989,3, 16. (7) Garry, J. H.; Handwerk, G.E. Petroleum Refining Technology and Economics, 2nd ed.; Marcel Dekker: New York, 1984. (8) ‘Test for Flash Point by Pensky M a r t e ~Closed Cup Teeter”, ASTM D 93-88; American Society for Testing and Materiala, Philadelphia, PA, 1986. (9) Manual of Mixing Fuels and Lubricants; Motor Oil (Hellas) Refineries, 1982; Vol. 4.
0 1991 American Chemical Society
Lois et al.
856 Energy & Fuels, Vol. 5, No. 6, 1991
Table I. Properties of the Basic Components A: Distillates
density, g/mL (15 "C) flash point, "C pour point, "C total sulfur, % distillation, "C IBP 10% 20 70 50 % 90 % FBP kinematic viscosity, cSt (37.8 "C)
LGAL 0.8277 80 -21 0.71
HGAL 0.8598 95 +I 1.41
LGIL 0.8332 72 -21 0.60
198 225 235 253 273 282 2.3
214 263 280 304 346 368 4.7
202 235 247 270 297 309 2.8
component" HGIL 0.8624 97 +5 1.00 225 270 290 320 364 385 6.1
LGZ 0.8218 76 -18 0.03
HGZ 0.8457 82 +7 0.07
KAL 0.7921 45
195 235 248 270 295 306 2.9
222 276 295 325 375 398 6.7
157 174 180 198 233 251 1.3
RZ1 0.9041 160 84 +29 130 0.25
RZ2 0.9086 240 118 +32 164 0.26
RS 0.9147
0.19
B: Residues
density, g/mL (15 "C) kinematic viscosity, cSt (37.8 "C) kinematic viscosity, cSt (50 "C) pour point, "C flash point, "C total sulfur, wt %
RALl 0.9548 388 168 +I1 120 3.02
RAL2 0.9614 780 348 +I5 144 3.14
RILl 0.9551 879 378 +18 120 2.43
comDonentb RIL2 0.9604 1180 460 +27 150 2.62
374 +43 159 0.27
I, LGAL, light gas oil from Arabian Light Crude; HGAL, heavy gas oil from Arabian Light Crude; LGIL, light gas oil from Iranian Light Crude; HGIL, heavy gas oil from Iranian Light Crude; LGZ, light gas oil from Zarzaitine Crude; HGZ, heavy gas oil from Zarzaitine Crude; KAL, kerosine from Arabian Light Crude. bRAL1, residue +330 "C from Arabian Light Crude; RAL2, residue +350 "C from Arabian Light Crude; RIL1, residue +330 "C from Iranian Light Crude; RIL2, residue +350 "C from Iranian Light Crude; RZ1, residue +350 "C from Zarzaitine Crude; RZ2,residue +370 "C from Zarzaitine Crude; RS, residue +370 "C from Sarir Crude.
Table 11. Measured Pour Point of Various Blends blend series 1 2 3 4 5 6 7 8 9 10 11
12 13
0.0 +21 +18 +29 +I8 +29 +18 +I1 +I8 +29 +7 +43 +43 +43
0.1 +17 +14 +25 +14 +28 +I7 +7 +I4 +26 +3 +41 +43 +41
0.2 +14 +11 +21 +11 +27 +I6 +5 +I1 +23 +I +38 +42 +38
0.3 +10 +8 +17 +7 +26 +15 +3 +8 +20 -1 +34 +41 +35
low pour point 0.4 +7 +5 +I3 +4 +25 +I4 +1 +6 +I7 -3 +31 +40 +30
ods,lOJ1or by using the blending indices: or through mathematical expressions.12 The present analysis is an effort to present reliable mathematical expressions that would predict accurately the final value of the main nonadditive properties of residual fuel-gas oil blends, i.e., pour point, flash point, and viscosity, thus obviating the need for tabulated values. Experimental Section In order to examine the mixing rules of the pour point, the flash point, and viscosity of fuel mixtures, mixed distillate fractions and residues of four crude oils were used, i.e., Arabian Light (paraffinic base), Iranian Light (mixed base), Zarzaitine (mixed base), and Sarir (paraffinic base). The properties of all the basic components that were employed are listed in Table I. All measurements were done according to the appropriate ASTM procedures. (10) Bland, W.F.;Davidson, R. L. Petroleum Processing Handbook; McGraw Hill: New York, 1967. (11)"Standard Viscosity-Temperature Charta for Liquid Petroleum Products", ASTM D 341-86, American Society for Testing and Materiala, Philadelphia, PA, 1986. (12) Woodle, R. A. NLCZ Spokesman, 1976, 40(3), 100.
component fraction 0.5 0.6 +5 +2 +2 0 +8 +3 +2 -1 +23 +21 +12 +11 0 -1 +2 +4 +14 +I1 -4 -5 +27 +23 +38 +35 +26 +21
0.7 -1 -2 -1 -3 +I9 +8 -2 0 +8 -6
+I7 +33 +15
0.8 -3 -4 -8 -6
+I5 +5 -3 -1 +5 -6 +11 +30 +5
0.9 -5 -6 -14 -8 +9 +I -4 -3 +2 -7 +4 +23 -5
1.0 -7 -7
-2 1 -9 -1 -4 -4 -4 -1 -7 -7 4-7 -18
Pour Point of Fuel Mixtures The common practice for the prediction of pour points of blends of residues with lighter fractions (gasoil or heavy kerosine) is based on experimentally determined and tabulated blending indices. An equation commonly used for the blended pour point is PPb = C [xiPPBIiPPi]/ C [xiPPBIi] (1) where PPb is the pour point of the blend, ppi the pour point of component i, x i the fraction of component i, by volume, and PPBIi the pour point blending index of component i. The blending indices are different for the gas oil and the residue. For the calculations, the pour point of every component uses its sign, and not the absolute value. In an effort to test eq 1, 13 series of gas oil-residue mixtures were prepared, whose lighter component content varied from 0 to loo%, and their pour point was experimentally determined. The results are shown in Table 11. Using eq 1and comparing the predicted with the experimentally observed values, quite satisfactory results were obtained with correlation coefficients approaching unity, the lowest being 0.974.
Energy & Fuels, Vol. 5, No. 6, 1991 857
Nonadditive Properties of Fuel Blends Table 111. Components of Blends for Pour Point Measurements blend series 1 2 3 4 5 6 7 8 9 10
high pour point component 70% RZ2 + 30% GAL 100% RILl 100% RZ1 100% RILl 100% RZ1 100% RILl 100% RALl 100% RILl 100% RZ1 88% RALl + 12% LGZ 100% RS 100% RS 100% RS
11 12 13
low pour point component 45% LGAL + 55% HGAL 45% LGAL + 55% HGAL 100% LGIL 55% LGAL 45% HGAL 35% LGAL + 65% RAL2 45% LGAL + 55% RAL2 30% LGAL + 70% HGAL 30% LGAL + 70% HGAL 15% LGZ 85% HGAL 45% LGIL + 55% HGAL 45% LGAL + 55% HGAL 20% HGAL + 80% RALl 100% LGZ
+
+
A
-
Blend Series 3 Blend Series 4 Calculated
- 3 8 . b " " 0.2
0.4
0.8 I
'
"
0.8
"
Volume Fraction (Low Pour Pt Comp)
1.0
Figure 2. Comparison of measured and calculated pour point for blend series 3 and 4.
-.-lo
'
-io
'
-Lo
'
'
io
'
Pour Point ("c)
4b
'
Eo
'
,b
Figure 1. Variation of the blending index as a function of the pour point for distillates and residues. However, the need in an automated refinery process is for a mathematical expression that would predict accurately the volumes of given fuels, according to the required pour point specifications. Graphical representation of the tabulated blending indices against pour point values show an exponential behavior. In an effort to obtain a single mathematical expression,a number of models were tested. The best fits, for both types of fuels, were obtained by using the following relation: Y = exp(a + bx) (2) where Y is the blending index, x is the pour point (K), and a and b are constants, and the proposed equations are as follows: a. for gas oils:
+
PPBI = exp(-4.55486 0.0178427PP) (3) b. for residual fuels: PPBI = exp(-15.5168 + 0.0524691PP) (4) the correlation coefficient in both cases being equal to 0.999. Figure 1 shows graphically the predicted blending indices, as a function of the pour point, for gas oils and residues, respectively. The predicted results of some of the blend series are shown in Figure 2, along with the experimentally determined values. In Figure 3 the measured pour points of all the blend series are compared with the calculated values. The overall fit is very good, whereas the maximum deviation observed for the pour point (2 "C) is within the repeatability limits of the ASTM method (3 "C).
-3oV' -30 -20 '
'
' -10
'
0'
' 10 '
a
20 ' ' 30'
'
'
40
'
50
Lois et al.
858 Energy & Fuels, Vol. 5, No. 6, 1991
Table IV. Measured Flash Point of Various Blends low flash Doint comDonent fraction blend series 1 2 3 4 5 6 7
8 9 10 11 12 13 14 15 16 11 18
0.1 101 87 132 136 93 119 92 90 105 92 97 112 98 110 92 137 112 93
0.0 144 108 150 164 164 150 150 130 120 160 120 150 108 144 144 159 159 159
0.2 89 78 122 125 81 107 81 80 95 81 87 100 93 98 80 125 98 81
0.4 77 69 111 112 69 96 69 69 85 69 76 88 85 86 69 112 86 69
0.3 82 74 115 117 74 101 74 73 89 76 81 92 88 92 74 117 92 14
0.5 74 65 107 107 66 92 65 65 81 65 73 84 82 82 66 108 83 66
0.6 71 62 105 104 63 89 63 63 78 63 70 80 79 79 63 104 80 63
0.8 67 58 99 99 58 84 58 58 74 58 66 76 75 75 58 100 75 58
0.7 69 60 101 101 60 86 60 60 76 60 68 78 77 77 60 102 78 60
0.9 65 57 97 97 57 82 56 56 73 56 65 74 73 73 57 98 73 56
Table V. Components of Blends for Flash Point Measurements blend high flash point series comDonent low flash Doint comDonent 100% RAL2 91% RALl + 9% LGZ 100% RIL2 100% RZ2 100% RZ2 100% RIL2 100% RILL 100% RZ1 100% RILl 96% RZ2 + 8% HGAL 100% RILl 100% RIL2 91% RALl + 9% LGZ 100% RAL2 100% RAL2 100% RS 100% RS 100% RS
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
L\'
"
"
"
83.5% LGIL + 16.5% KAL 60% LGIL + 40% KAL 100% HGAL 100% HGAL 60% LGIL 40% KAL 94% HGAL + 6% KAL 60% LGIL 40% KAL 60% LGIL + 40% KAL 87.5% LGIL + 12.5% KAL 60% LGIL + 40% KAL 83.5% LGIL + 16.5% KAL 100% LGIL 100% LGIL 87.5% LGIL + 12.5% KAL 60% LGIL 40% KAL 100% HGAL 100% LGIL 60% LGIL + 40% KAL
+ +
+
'
0 0
"
"
'
A
1.0 63 55 95 95 55 80 55 55 71 55 63 72 72 71 55 95 72 55
Blend Serier 11 Blend Seriea Q
-100
u
-
-
Calculated
Y
4
"dC a c
90
c
80-
a
70
-
-
68.Lo"
0.2
0.4 "
0.8 "
0.8 "
'
1.0
Volume Fraction (Low FP Component) Figure 5. Comparison of measured and calculated flash point for blend series 9 and 11. 170
1
Computed FPBI Actual FPBI
u
150
v 4
.-C0 130
a
.
.-e a
d
-
.-
%e I r40
80
80
100
120
140
180
180
505K '
7b
'
Qo
'
1;o
'
A0 '
1o;
'
do
Flash Point ("C) Figure 4. Variation of the blending index as a function of the flash point.
Measured Flash Point ("C) Figure 6. Comparison of measured and calculated flash point for all the blends.
where F is the flash point (OC)and a, b, c, d are constants with the following values: a = -4.42527 X lo-'; b = 2.9024 X c = -0.0956904; d = 9.83274. Figure 4 shows the shape of the calculated curve of flash point blending index as a function of flash point, along with actual values of FPBI. Some of our experimental results from two blend series are shown in Figure 5, together with the calculated values from eqs 5 and 6. The computation of the flash point of the blend from its cal-
culated blending index employs the inverse (logarithmic) relation that has the form FP = -0.-069662(1n FPBI)3 + 1.76638(1nFPBI)2 27.7304 In FPBI + 163.829 (7)
All of the flash point measurementsare shown in Figure 6 along with the calculated values; the overall fit, covering all 18 series of blends with flash points ranging from 55 to 165 OC, is again very good.
Energy & Fuels, Vol. 5, No. 6, 1991 859
Nonadditive Properties of Fuel Blends
Table VI. Measured Kinematic Viscosity of Various Blends (cSt) low viscosity component fraction blend series
0.0
0.1
0.2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2 10 220 23a 24"
569 879 879 879 614 736 569 602 780 903 827 805 614 180 717 370 980 980 614 614 374 374 374 374
515 380 735 755 530 620 485 482 510 638 503 575 425 108 340 310 750 449 308 520 169 358 231 322
465 190 638 660 468 530 414 392 352 449 367 416 344 67 175 255 569 212 154 435 90 321 156 264
0.3 413 84 538 575 415 455 350 314 254 332 274 300 277 44 93 208 454 112 84 361 49 293 104 225
0.4 380 50 450 512 360 398 301 262 176 240 210 220 235 29 54 180 358 61 53 304 34 278 75 180
0.5 336 31.2 393 440 323 338 262 210 121 184 167 165 190 21 32 150 281 35 35 258 19.2 240 54 150
0.6 303 17.7 331 395 281 306 226 176 91 140 124 130 164 14.5 20 118 229 21.8 19.2 220 15.0 232 40 136
0.7 275 11.0 287 343 254 254 198 144 74 108 108 94 136 10.7 13.4 108 180 14.0 13.0 185 10.2 219 30 106
0.8 254 8.0 249 299 224 230 170 128 58 82 80 64 110 8.0 9.0 92 147 9.3 9.0 159 7.6 201 25 99
0.9 236 5.5 219 269 198 200 151 108 44.2 67 71 54 97 6.0 6.4 78 121 6.5 6.5 138 6.0 180 21.1 80
1.0 210 4.7 191 240 179 179 129 89 32.5 53 49 49 82 4.7 4.7 68 100 4.7 4.7 120 4.0 168 15.2 73
Measurements at 50 O C .
Blend Series 2 A Blend Series 17
10' 1
'
""""
10
'
""""
100
'
' ' ' ' ' ' t l
1000
'
"
L
c
j
u
.
10000
Kinematic Viscosity (cSt)
Figure 7. Variation of the blending index as a function of the kinematic viscosity.
Viscosity of Fuel Mixtures In an effort to compare the results obtained by the existing methods, 24 binary blends of gas oil-residual fuel were prepared (Table VII) and their viscosities were experimentally determined. Oil refineries frequently use the blending index method
VBIb = CwiVBIi (8) where VBIb is the viscosity blending index, by weight, VBIi the viscosity blending index of component i, and wi = fraction of component i , by weight. Our analysis shows that the ASTM graphical method" predicts the blended viscosity with an accuracy ranging from 3.15 to 4.16%, whereas eqs 9-1 1, which were proposed by Woodle12and are based on the well-known Walther viscosity relation, deviate by 2.05-3.48%. Y1 = In In (uA + 0.8) (9) Y2 In In (uB + 0.8) (10) (11) Y3 = xA(Y1 - Y2) + Y2 ub = exp(exp(Y3)) - 0.8 (12)
0.0
Calculated 0.2
0.4
0.6
1.0
0.6
Weight Fraction (Low Viscosity Component)
Figure 8. Comparison of measured and calculated kinematic viscosity for blend series 2 and 17. 100OL
I
I
1
,,I
10
100,
I
1000
Measured Kinematic Viscosity (cSt)
Figure 9. Comparison of measured and calculated kinematic Viscosity for all the blends.
where V A is the kinematic viscosity of component A, U B the kinematic viscosity of component B, ub the kinematic viscosity of the mixture, and xAthe fraction of component
Energy & Fuels 1991,5, 860-866
860
Table VII. ComDonents of Blends for Viscosity Measurements blend series high-viscosity component low-viscosity component 96.5% RAL2 + 3.5% HGAL 97.5% RZ2 + 3.5% HGZ 1 2 100% RILl 100% HGAL 3 100% RILl 96% RZ2 + 4% HGZ 4 100% RILl 100% HGZ 97% RAL2 + 3% HGAL 94.5% RZ2 + 5.5% HGZ 5 98% RILl + 2% HGAL 94.5% RZ2 + 5.5% HGZ 6 96.5% RAL2 + 3.5% HGAL 88% RZ2 + 12% HGZ 7 87% RZ1+ 13% HGZ 96% RILl + 3% HGAL 8 60% RZ1+ 40% HGZ 100% RILl 9 74% RZ1+ 26% HGZ 97% RIL2 + 3% HGIL 10 66% RZ2 + 34% HGZ 11 96% RIL2 + 4% HGIL 66% RZ2 + 34% HGZ 12 99% RILl + 1% HGAL 85% RZ2 + 15% HGZ 97% RILl + 3% HGAL 13 100% HGAL 14 94.5% RZ2 + 5.5% HGZ 100% HGAL 15 99% RAL2 + 1% HGZ 80% RZ1+ 20% HGZ 99% RAL2 + 1 % HGAL 16 98% RZ2 + 2% HGIL 90% RZ1+ 10% HGZ 17 100% HGAL 18 98% RZ2 + 2% HGIL 97% RAL2 + 2% HGAL 100% HGAL 19 97% RALS + 2% HGAL 86% RZ2 + 14% HGZ 20 21 100% RS 100% HGZ 22 100% RS 100% RALl 48% RALl + 52% HGIL 23 100%RS 85% RALl + 15% HGIL 24 100% RS
i in the mixture, by volume. Since the refineries prefer the tabulated blending indices for predicting the blended viscosity, it was decided to attempt to express mathematically the relation between
VBI and kinematic viscosity. The following expression was found to give very good results VBI = exp(4.179757~~~~""~~) (13) where VBI is the viscosity blending index, by weight, and u the kinematic viscosity (cSt). The correlation coefficient with actual blending indices is 0.999, and a graphic representation of the function is shown in Figure 7. All of our results in the viscosity blending experiments are presented in Table VI, whereas Figure 8 is a schematic representation of actual and calculated viscosity values for two of the blend series. Finally, Figure 9 shows a comparison of all 264 of the measured viscosity values with the values calculated from relations 8 and 13. Conclusions Mathematical expressions are presented for some nonadditive properties for mixing gas oil and residual fuel fractions. Excellent correlations are obtained for the blended values of the pour point, the flash point, and viscosity, thus obviating the need for tabulated values of the blending indices, which are currently used in industry. Acknowledgment. We thank Petrola Refinery, Elefsis, Greece, for supplying us with most of the crude oil components that were used in this study.
Behavior of Oxidized Type I1 Kerogen during Artificial Maturation Patrick Landais,*ft Raymond Michels,t Jacky Kister,* Jean-Marie Derepge,s and Zouhir Benkheddat CREGU and GDR CNRS-CREGU, BP 23,54501 Vandoeuure-16s-Nancy Cedex, France, Centre de Spectroscopie Mole'culaire, Faculte' des Sciences et Techniques St. Je'rGme, 13397 Marseille Cedex, France, and CRIS, Universitd de Louuain-la-Neuue, 1 Place Louis Pasteur, 1348 Louvain-la-Neuve, Belgium Received May 10, 1991. Revised Manuscript Received July 5, 1991 A series of artificially oxidized type I1 kerogens (ventilated oven, 140 "C, 8-256 h) from the Paris Basin (France) has been pyrolyzed in cold-seal autoclaves at temperatures ranging between 250 and 450 OC for 24 h at 100 MPa. Oxidates and pyrolysates have been characterized by I3C solid-state NMR, FTIR spectroscopy, Rock-Eva1 pyrolysis, elemental analysis, and CHC13extraction. Results indicate that oxidation is responsible for an important decrease of the petroleum potential and for the increase of different oxygen-bearing functions' (carbonyl, carboxyl, esters, ethers) concentration. The behavior of the different oxidates during artificial maturation is characterized by two distinct stages: oxygen removal (250-300 "C)and hydrocarbon production (300-450 "C). It is shown that oxidation induces an important decrease of the hydrocarbon yield during maturation and that no regeneration of petroleum potential can be observed. Comparison of the most oxidized kerogen (256 h) with an unoxidized type I11 coal of similar initial elemental composition has also been carried out.
Introduction The effects of oxidation on organic matter composition have been widely studied in the fields of coal processing, soil sciences, or petroleum geochemistry. Increases of alkali CREGU and GDR CNRS-CREGU.
* Facult6 des Sciences et Techniques St. JCrBme. 1 Universitg
de Louvain-la-Neuve.
solubility' and aromaticity,2 decrease of coking quality? and modifications of optical properties as well as pyrolysis products distribution4 have been quoted among the main (1)Jensen, E. J.; Melnyk, N.; Wood,J. C.; Berkowitz N. Ado. Chem. Ser. 1964,55, 621-642. (2) Dereppe, J. M.; Moreaux, C.; Landais, P.; Monthioux, M. Fuel 1987,67, 764-770. (3) Seki, H.; Ito, 0.; Lino, M. Fuel 1990, 69, 1047-1051.
0887-0624/91/2505-0860$02.50/00 1991 American Chemical Society
